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Explains the console - http://buildinternet.com/2010/12/debugging-javascript-behind-the-scenes/
Useful JavaScript Tricks
Resolution
In the browser address bar,
To determine the actual size of the browser window, use the following properties:
Internet Explorer (backward-compatibility mode):
document.body.offsetWidth, document.body.offsetHeight
Internet Explorer (standards mode, document.compatMode=='CSS1Compat'):
document.documentElement.offsetWidth, document.documentElement.offsetHeight
Most other browsers:
window.innerWidth, window.innerHeight